1. Field of the Invention
This invention relates to a method of automatically detecting the locations of the frame lines of a reversal film as it is supplied to a processing station, such as a cutting and mounting station, a notching station or the like, so that the frame lines can be used as reference marks for the positioning of the film in the processing station, wherein the film is moved past optoelectronic scanning means in steps which amount to only a fractional part of the normal width of a frame line, said optoelectronic scanning means generate an analog volage which represents the accumulated light transmission of the film in a scanned area which extends at right angles to the direction of travel of the film substantially across the picture area of the film and has a width which is only a fractional part of a normal width of a frame line, and the extreme value of said voltage obtained during a scanning of at least one normal frame length and corresponding to the lowest light transmission is evaluated as a representation of the light transmission of the scanned film at a frame line.